China should phase out its unpopular one-child policy and let families have two children by 2015, an influential think-tank with close links to the government has proposed.

The suggestion comes from the China Development Research Foundation (CDRF), adding to growing calls for a relaxation of a policy first introduced over 30 years ago.

It would see the world's most populous country eventually abandon a measure that has been blamed for creating a demographic timebomb, with an ageing population foreshadowing huge economic and social problems.